JP6037861B2 - Seam welding apparatus and seam welding method - Google Patents

Description

  The present invention relates to a seam welding apparatus and a seam welding apparatus that perform resistance welding by sandwiching a workpiece in which at least two base materials are laminated by a pair of roller electrodes, and applying pressure and energization while rotating the pair of roller electrodes. Regarding the method.

  Conventionally, a method for managing the temperature of the nugget in seam welding is known (see, for example, Patent Document 1). In Patent Document 1, the welding conditions of the welding temperature are set so that the nugget ratio obtained by dividing the nugget length at the joint surface of the weld by the length of the joint surface of the weld is within the range of 40 to 60%. And weld.

Japanese Patent No. 3575287

Conventionally, when seam welding a workpiece in which at least two base materials are laminated, since the workpiece is small, seam welding is performed by moving the small workpiece to a pair of fixedly arranged roller electrodes. It was.
However, in recent years, in order to perform seam welding of a large workpiece, a welding apparatus main body provided with a pair of roller electrodes is mounted on a robot, and the welding apparatus main body is moved with respect to the workpiece by the robot to perform seam welding.

At this time, since each base material of the workpiece is individually formed by press molding or the like, the size of the gap between the base materials in the workpiece is not constant at the welding target portion of the workpiece.
When seam welding is performed under the same welding conditions when the size of the gap between the base materials in the workpiece is different at the welding target portion of the workpiece, the welding state of the welding target portion may vary.
For example, if the welding current value supplied to the workpiece is the same when the size of the gap between the base materials in the workpiece is different, the larger the gap between the base materials in the workpiece, the higher the electrical resistance and the nugget grows. Since it is easy, the welding strength varies and the quality of seam welding is lowered.

  The present invention is for solving the above-mentioned problems, and its purpose is adapted to welding conditions for growing nuggets to be equal in size even when the sizes of the gaps between the base materials in the workpiece are different. It is an object of the present invention to provide a seam welding apparatus and a seam welding method for maintaining the welding state constant and improving the quality of seam welding.

  (1) A welding device main body (for example, a welding device main body 20 described later) and a workpiece (for example, a base material W1 or W2 described later) provided on the welding device main body and laminated (for example, base materials W1 and W2 described later) A pair of roller electrodes (for example, a pair of roller electrodes 21 to be described later) that roll while sandwiching a workpiece W (to be described later), and a traveling direction (for example, a traveling direction to be described later) from the pair of roller electrodes of the welding apparatus main body. A) A heat source (for example, a heat source 22 described later) that is provided in front and heats one surface (for example, an upper surface Wa described later) of the workpiece, a heating position by the heat source, and a clamping position by the pair of roller electrodes Temperature measuring means (for example, a second temperature sensor 24 described later) for measuring the temperature (for example, a temperature Tb described later) of the other surface (for example, a lower surface Wb described later) of the workpiece, and the temperature measurement Based on the temperature of the other surface of the workpiece measured by the means, the size of the gap between the base materials in the workpiece (for example, GAP described later) is estimated, and the welding conditions ( For example, a seam welding apparatus comprising control means (for example, a control device 30 described later) for adjusting a welding current I value described later.

According to the invention of (1), the control means heats one surface of the workpiece, measures the temperature of the other surface of the workpiece on the downstream side in the traveling direction of the heating position, and determines the measured temperature of the other surface of the workpiece. Based on this, the size of the gap between the base materials in the workpiece is estimated, and the welding conditions are adjusted according to the size of the gap.
That is, the heat heated at the heating position is transferred from one surface of the workpiece to the other surface. At this time, the larger the gap between the base materials in the workpiece, the more difficult the heat is transferred to the other surface of the workpiece. That is, the amount of heat transferred from one surface of the workpiece to the other surface and the size of the gap between the base materials in the workpiece have an inversely proportional correlation.
For this reason, when the correlation between the temperature of the other surface transferred from one surface of the workpiece and the size of the gap between the base materials in the workpiece is specified in advance, the temperature of the other surface of the workpiece after heating is measured. By doing so, the size of the gap between the base materials in the workpiece can be estimated. Thereby, welding conditions can be adjusted according to the magnitude | size of the clearance gap between the base materials in a workpiece | work.
Therefore, even when the size of the gap between the base materials in the workpiece is different, the welding state is maintained constant by adapting to the welding conditions for growing the nugget to the same size, and the quality of seam welding is improved. be able to.

  (2) The seam welding apparatus according to (1), wherein the control means adjusts a welding current value to be supplied to the pair of roller electrodes according to the size of the gap.

According to invention of (2), a control means adjusts the welding current value supplied to a pair of said roller electrode according to the magnitude | size of the clearance gap between the base materials in a workpiece | work.
That is, the larger the gap between the base materials in the workpiece, the higher the electrical resistance of the workpiece, and the nugget grows only by supplying a small welding current, and a high welding strength can be obtained. That is, in order to obtain a constant welding strength, the size of the gap between the base materials in the workpiece and the size of the welding current have an inversely proportional correlation.
For this reason, if the correlation between the size of the gap between the base materials in the workpiece and the magnitude of the welding current is specified in advance, welding for obtaining a constant welding strength according to the size of the gap between the base materials in the workpiece The current value can be estimated.
Thereby, the welding current value supplied to the pair of roller electrodes can be adjusted according to the size of the gap between the base materials in the workpiece, and the welding condition can be adapted to grow the nugget to the same size.

  (3) The control means estimates a contact area size (for example, CAS described later) between the base materials in the workpiece when the pair of roller electrodes passes according to the size of the gap. The seam welding apparatus according to (2), wherein a welding current value supplied to the pair of roller electrodes is adjusted according to the size of the contact area.

According to the invention of (3), the control means estimates the size of the contact area between the base materials in the workpiece when the pair of roller electrodes passes according to the size of the gap between the base materials in the workpiece. The welding current value supplied to the pair of roller electrodes is adjusted according to the size of the contact area.
That is, the larger the gap between the base materials in the workpiece, the smaller the contact area between the base materials in the workpiece when the pair of roller electrodes pass. That is, the size of the gap between the base materials in the workpiece and the size of the contact area between the base materials in the workpiece have an inversely proportional correlation.
And the larger the contact area between the base materials in the workpiece, the lower the electrical resistance of the workpiece, and the nugget will not grow unless a large welding current is supplied, and high welding strength cannot be obtained. That is, in order to obtain a constant welding strength, the size of the contact area between the base materials in the workpiece and the magnitude of the welding current have a proportional correlation.
Therefore, there is a correlation between the size of the gap between the base materials in the workpiece and the size of the contact area between the base materials in the workpiece, and the correlation between the size of the contact area between the base materials in the workpiece and the magnitude of the welding current. Is specified in advance, a welding current value for obtaining a constant welding strength can be estimated according to the size of the gap between the base materials in the workpiece.
Therefore, the welding current value for obtaining a constant welding strength is set according to the size of the gap between the base materials in the workpiece to maintain the welding state constant, and the quality of seam welding is improved by making the welding strength uniform. Can be improved.

  (4) A work (for example, a work W described later) in which at least two base materials (for example, base materials W1, W2 described later) are stacked with a pair of roller electrodes (for example, a pair of roller electrodes 21 described later). A seam welding method in which resistance welding is performed by pressing and energizing the pair of roller electrodes while rotating the pair of roller electrodes, and a traveling direction (for example, a traveling direction A to be described later) from a sandwiching position by the pair of roller electrodes ), A heating step (for example, steps S51 and S53 to be described later) for heating one surface (for example, an upper surface Wa to be described later), a heating position in the heating step, and a sandwiching position by the pair of roller electrodes Measuring step (for example, step S54 described later) for measuring the temperature (for example, temperature Tb described later) of the other surface (for example, lower surface Wb described later) of the workpiece, Based on the measured temperature of the other surface of the workpiece, the size of a gap between the base materials in the workpiece (for example, GAP described later) is estimated, and welding conditions (for example, according to the size of the gap) A seam welding method including an adjustment step (for example, steps S55, S56, S57, S5a, S5b, S5c, and S5d, which will be described later) for adjusting a welding current I value described later.

  According to the invention of (4), the same actions and effects as those of the invention of (1) can be achieved.

  (5) The seam welding apparatus according to (4), wherein the adjustment step adjusts a welding current value supplied to the pair of roller electrodes according to the size of the gap.

  According to the invention of (5), the same actions and effects as those of the invention of (2) can be achieved.

  (6) The adjustment step estimates a contact area size (for example, CAS described later) between the base materials in the workpiece when the pair of roller electrodes passes according to the size of the gap. The seam welding method according to (5), wherein a welding current value supplied to the pair of roller electrodes is adjusted according to the size of the contact area.

  According to the invention of (6), the same actions and effects as those of the invention of (3) can be achieved.

  According to the present invention, even when the size of the gap between the base materials in the workpiece is different, the welding condition for growing the nugget to the same size is adapted to maintain the welding state constant, and the seam welding It is possible to provide a seam welding apparatus and a seam welding method that improve quality.

It is a schematic structure figure showing the seam welding device concerning a 1st embodiment of the present invention. It is a perspective view which shows the welding apparatus main body which concerns on the said embodiment, and its periphery. It is a figure which shows the temperature-GAP characteristic which concerns on the said embodiment. It is a figure which shows the GAP-welding current characteristic which concerns on the said embodiment. It is a flowchart which shows the procedure which implements the seam welding using the seam welding apparatus which concerns on the said embodiment. It is a flowchart which shows the detailed procedure of the seam welding which concerns on the said embodiment. It is a figure which shows the time change of the welding conditions which concern on the said embodiment. It is a figure which shows the temperature-GAP characteristic which concerns on 2nd Embodiment of this invention. It is a figure which shows the GAP-CAS characteristic which concerns on the said embodiment. It is a figure which shows the CAS-welding current characteristic which concerns on the said embodiment. It is a flowchart which shows the detailed procedure of the seam welding which concerns on the said embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
First, with reference to FIG. 1 and FIG. 2, the structure of the seam welding apparatus 1 which concerns on 1st Embodiment is demonstrated.
FIG. 1 is a schematic configuration diagram showing a seam welding apparatus 1. FIG. 2 is a perspective view showing the welding apparatus main body 20 and its periphery.

  The seam welding apparatus 1 includes a robot 10, a welding apparatus main body 20, and a control apparatus 30.

The robot 10 is an industrial robot having an articulated arm 11. A base 12 connected to the base end side of the arm 11 is installed on a floor surface of a factory or the like, and the arm is switched to an arbitrary posture by a program operation. 11 can be changed to an arbitrary state.
A base 12 of the robot 10 is rotatable, and the robot 10 has a rotation angle detection unit 13 that outputs a signal corresponding to the rotation angle of the base 12. The arm 11 of the robot 10 has a six-axis joint, The robot 10 includes an axis angle detection unit 14 that outputs a signal corresponding to the axis angle of each joint of the arm 11.

The welding apparatus body 20 is attached to the tip of the arm 11 of the robot 10.
The welding apparatus body 20 includes a pair of roller electrodes 21, a heat source 22, a first temperature sensor 23, and a second temperature sensor 24.

  The pair of roller electrodes 21 includes a first roller electrode 21a disposed above and a second roller electrode 21b disposed below, and sandwiches a workpiece W in which at least two or more base materials W1 and W2 are stacked. Roll.

  The heat source 22 is provided in front of the pair of roller electrodes 21 of the welding apparatus body 20 in the traveling direction A of the welding apparatus body 20 and heats the upper surface Wa of the workpiece W. As the heat source 22, for example, a heating element that generates heat when energized, such as an induction heating device or a coil heater, is used.

  The first temperature sensor 23 measures the temperature Ta of the upper surface Wa of the workpiece W between the heating position by the heat source 22 and the clamping position by the pair of roller electrodes 21.

  The second temperature sensor 24 is disposed below the first temperature sensor 23 and measures the temperature Tb of the lower surface Wb of the workpiece W between the heating position by the heat source 22 and the clamping position by the pair of roller electrodes 21.

  As the first temperature sensor 23 and the second temperature sensor 24, for example, a non-contact type temperature sensor that can measure the temperature of the workpiece W in a non-contact state is used.

  As shown in FIG. 2, the welding apparatus main body 20 further includes a base 40, a first support unit 50, a second support unit 60, and a moving mechanism 70.

The base 40 is held at the tip of the arm 11 of the robot 10 and supports the heat source 22, the first temperature sensor 23, and the second temperature sensor 24.
The first support unit 50 is configured to be movable with respect to the base 40 and supports the first roller electrode 21a.
The second support unit 60 is fixed to the base portion 40 and supports the second roller electrode 21b.
The moving mechanism 70 moves the first support unit 50.

  The base 40 extends in the vertical direction (X direction) during standby of the welding apparatus main body 20 and is formed into a rectangular parallelepiped shape, a holding plate 42 provided on an upper end portion 41 a of the supporting column 41, and a holding plate 42. A mounting portion 43 rotatably attached to the tip of the arm 11 of the robot 10 while being fixed to the upper surface, and a welding power source 44 provided on one side surface 41b of the support column 41 are provided.

  The holding plate 42 includes a flat portion 42a on which the mount portion 43 is disposed above, a bent portion 42b bent downward along a side surface 41c opposite to the side surface 41b provided with the welding power source 44 of the support column 41, and a bent portion 42b. A projecting portion 42c projecting outward from the lower end of the portion 42b.

  The support column 41 has the first support unit 50 movable below the projecting portion 42c on the side surface 41c of the projecting portion 42c of the holding plate 42 projecting, and the second support unit 60 further extends from the first support unit 50. Have fixed below. The first support unit 50 and the second support unit 60 are arranged in parallel in the X direction on the side surface 41 c of the support column 41.

  The welding power source 44 outputs a current used in the welding apparatus body 20 such as supplying a welding current to the pair of roller electrodes 21 or supplying a current to the heat source 22.

  The moving mechanism 70 includes a pair of guide rails 71 extending in the X direction below the bent portion 42b of the holding plate 42 on the side surface 41c opposite to the side surface 41b provided with the welding power source 44 of the support column 41, and the first support unit 50. And a cylinder 73 that is provided on the overhanging portion 42c and drives the rod portion 72 in the X direction.

  The first support unit 50 includes a housing 51 to which the rod portion 72 is fixed, a support shaft member 52 that is provided on the first roller electrode 21a and extends in the horizontal direction (Y direction) when the welding apparatus body 20 is on standby. A spindle rotating mechanism 53 that rotates the first roller electrode 21a in a direction (Z direction) orthogonal to the X direction and the Y direction, and an electrode rotation motor 54 that rotates the first roller electrode 21a are provided.

  The housing 51 has a pair of guide grooves 51 a that engage with the pair of guide rails 71. The first support unit 50 can move smoothly in the X direction in accordance with the drive in the X direction by the cylinder 73 by the pair of guide grooves 51 a of the housing 51 engaging the pair of guide rails 71.

  The support shaft member 52 connects a first shaft portion (not shown) fixed to the first roller electrode 21a, a second shaft portion connected to the electrode rotation motor 54, and the first shaft portion and the second shaft portion. And a universal joint. For example, a constant velocity joint can be used as the universal joint.

  The support shaft turning mechanism 53 includes a support shaft support member (not shown) located in the housing 51, a support shaft turning motor 53a that rotationally drives the support shaft support member, and the power of the support shaft turning motor 53a. A power transmission mechanism (not shown) for transmitting to the support member.

  The second support unit 60 has basically the same configuration as the first support unit 50. For this reason, the 2nd support unit 60 attaches | subjects the same referential mark to the structure which is common in the 1st support unit 50, and abbreviate | omits description.

The second support unit 60 is fixed to the support column 41 in a state where the first support unit 50 is inverted in the X direction. For this reason, the second support unit 60 does not have the guide groove 51 a of the housing 51.
The first support unit 50 and the second support unit 60 are arranged with the first roller electrode 21a and the second roller electrode 21b aligned in the X direction.

  The control device 30 includes a robot control unit 31, a heat source control unit 32, a welding power source control unit 33, an electrode rotation motor control unit 34, a support shaft rotation motor control unit 35, a cylinder control unit 36, and a memory. Part 37.

The robot control unit 31 controls the robot 10 to change the posture of the robot 10 and the arm 11.
The heat source control unit 32 controls the heat source 22 by adjusting the amount of current supplied to the heat source 22.
The welding power source control unit 33 controls the welding power source 44.
The electrode rotation motor controller 34 controls the electrode rotation motor 54.
The spindle rotation motor control unit 35 controls the spindle rotation motor 53a.
The cylinder control unit 36 controls the cylinder 73.

  The storage unit 37 stores teaching data and welding control data of the robot 10. The welding control data includes movement speed data regarding the movement speed of the welding apparatus main body 20 fixed to the tip of the arm 11 of the robot 10 and rotation speed data regarding the rotation speed of the pair of roller electrodes 21.

  Moreover, the memory | storage part 37 further memorize | stored the temperature-GAP characteristic shown in FIG. 3, and the GAP-welding current characteristic shown in FIG.

FIG. 3 is a diagram illustrating temperature-GAP characteristics, where the horizontal axis represents the temperature Tb of the lower surface Wb transferred from the upper surface Wa of the workpiece W, and the vertical axis represents the distance between the base materials W1 and W2 in the workpiece W. The size of the gap (hereinafter referred to as GAP). For example, GAP is defined in three stages of G0, G1, and G2. In addition, you may prescribe | regulate GAP other than three steps.
Here, the temperature-GAP characteristic defines an inversely proportional correlation between the temperature Tb of the lower surface Wb transferred from the upper surface Wa of the workpiece W and the GAP. The temperature-GAP characteristic is based on the correlation that the heat transferred from the upper surface Wa of the workpiece W is less likely to be transferred to the lower surface Wb of the workpiece W as the GAP between the base materials W1 and W2 in the workpiece W increases. Yes. The temperature-GAP characteristic is set in advance by experiments or the like.

FIG. 4 is a diagram showing GAP-welding current characteristics, where the horizontal axis indicates GAP and the vertical axis indicates the magnitude of the welding current I. For example, the welding current I is defined in three stages of Ia, Ib, and Ic. In addition, you may prescribe | regulate welding current I other than three steps.
The GAP-welding current characteristic defines an inversely proportional correlation between GAP and the magnitude of the welding current in order to obtain a constant welding strength. The GAP-welding current characteristic shows that the larger the GAP between the base materials W1 and W2 in the workpiece W, the higher the electrical resistance of the workpiece W, and the nugget grows only by supplying a small welding current to obtain high welding strength. Based on the correlation that can be. The CAS-welding current characteristic is set in advance through experiments or the like.

Next, a procedure for performing seam welding using the seam welding apparatus 1 will be described with reference to FIGS.
FIG. 5 is a flowchart showing a procedure for performing seam welding using the seam welding apparatus 1. FIG. 6 is a flowchart showing a detailed procedure of seam welding.

  As shown in FIG. 5, first, the workpiece W is set at a predetermined position (step S1). As the workpiece W, for example, a large workpiece in which at least two base materials W1 and W2 are stacked, such as a body of an automobile, can be used. The base materials W1 and W2 in the workpiece W are individually formed by press molding or the like, and the size of the gap between the base materials W1 and W2 is not constant.

  Subsequently, the control device 30 creates teaching data for the robot 10 (step S2) and stores the created teaching data in the storage unit 37.

Next, the robot control unit 31 controls the robot 10 to change the posture of the robot 10 and the arm 11 to move the welding apparatus main body 20 to the welding point (step S3). Specifically, the robot control unit 31 moves the welding apparatus main body 20 so that the welding point of the welding target portion of the workpiece W is positioned between the pair of roller electrodes 21.
The welding apparatus main body 20 moved to the welding point brings the lower second roller electrode 21b into contact with the lower surface Wb of the workpiece W.

  Next, the cylinder controller 36 controls the cylinder 73 to move the first support unit 50 to the lower second support unit 60 side, and sandwich and pressurize the workpiece W with the pair of roller electrodes 21 (step S4). ).

  Subsequently, the control device 30 performs seam welding on the welding point (step S5). Specifically, the control device 30 performs seam welding by performing processing of steps S50 to S58 described later shown in FIG.

  That is, the electrode rotation motor control unit 34 drives the electrode rotation motor 54 to rotate the pair of roller electrodes 21, thereby energizing the pair of roller electrodes 21 with the pair of roller electrodes 21 in the welding point. (Step S50).

  Subsequently, the heat source control unit 32 energizes the heat source 22 to generate heat, and heats the upper surface Wa of the workpiece W with the heat source 22 (step S51).

  Subsequently, the control device 30 measures the temperature Ta of the upper surface Wa of the workpiece W with the first temperature sensor 23 (step S52). Here, the measurement position where the first temperature sensor 23 measures the upper surface Wa of the workpiece W is downstream in the traveling direction A of the welding apparatus body 20 from the heating position where the heat source 22 heats the upper surface Wa of the workpiece W.

  Subsequently, the heat source control unit 32 determines the temperature Ta of the upper surface Wa of the workpiece W measured by the first temperature sensor 23 so that the temperature Ta of the upper surface Wa of the workpiece W measured by the first temperature sensor 23 falls within a predetermined range. Accordingly, the energization amount supplied to the heat source 22 is adjusted (step S53).

  Subsequently, the control device 30 measures the temperature Tb of the lower surface Wb of the workpiece W with the second temperature sensor 24 (step S54). Here, the measurement position where the second temperature sensor 24 measures the lower surface Wb of the workpiece W is downstream in the traveling direction A of the welding apparatus body 20 from the heating position where the heat source 22 heats the upper surface Wa of the workpiece W. The second temperature sensor 24 measures the temperature Tb transferred from the upper surface Wa to the lower surface Wb of the workpiece W.

  Subsequently, the control device 30 uses the temperature-GAP characteristic shown in FIG. 3 stored in advance in the storage unit 37 and obtains the GAP determined according to the temperature Tb of the lower surface Wb of the workpiece W measured by the second temperature sensor 24. Is calculated (step S55). Here, the calculated GAP is the size of the gap between the base materials W1 and W2 in the workpiece W at the measurement position measured by the second temperature sensor 24, and is divided into three stages G0, G1, and G2. It is a thing.

Subsequently, the control device 30 calculates the value of the welding current I obtained according to the calculated GAP using the GAP-welding current characteristic shown in FIG. 4 stored in advance in the storage unit 37 (step S56). . Here, the calculated value of the welding current I is a welding current value necessary for obtaining a constant welding strength at the measurement position measured by the second temperature sensor 24, and is divided into three stages G0 and G1. , G2 is divided into three stages of Ia, Ib, and Ic corresponding to GAP.
And the control apparatus 30 once memorize | stores the value of the welding current I in the measurement position measured with the calculated 2nd temperature sensor in the memory | storage part 37 once.

  Subsequently, the welding power source control unit 33 supplies a welding current to the pair of roller electrodes 21 (step S57). Here, the welding current supplied to the pair of roller electrodes 21 is a measurement position measured by the second temperature sensor 24 in the past once stored in the storage unit 37, and is a position where the pair of roller electrodes 21 are currently sandwiched. The value of welding current I is supplied. Thereby, resistance welding is obtained in which a constant welding strength is obtained at the position where the pair of roller electrodes 21 are sandwiched.

  And the control apparatus 30 determines whether the seam welding was complete | finished about all the welding points (step S58). When it is determined that the seam welding has not been completed (step S58 → NO), the process proceeds to step S50, and the processes after step S50 are performed.

  On the other hand, when it is determined that the seam welding has been completed (step S58 → YES), the cylinder control unit 36 controls the cylinder 73 to move the first support unit 50 away from the second support unit 60 upward. The pressure of the workpiece W by the pair of roller electrodes 21 is released (step S6).

Next, the robot control unit 31 controls the robot 10 to change the posture of the robot 10 and the arm 11 to move the welding apparatus main body 20 to the standby position (step S7).
Thus, the procedure for performing seam welding is completed.

FIG. 7 is a diagram showing a change over time in the welding conditions according to the present embodiment. The horizontal axis in FIG. 7 is time, and the vertical axis is the temperature Tb of the lower surface Wb of the workpiece W measured by the second temperature sensor 24.
As shown in FIG. 7, GAP is estimated according to the temperature Tb of the lower surface Wb of the workpiece W after heating. And the value of the welding current I can be adjusted according to GAP. As a result, when the GAP between the base materials W1 and W2 in the workpiece W is different, the value of the welding current I supplied to the workpiece W is optimally adjusted, and welding is performed in accordance with the welding conditions for growing the nugget to an equal size. The state can be kept constant and the quality of seam welding can be improved.

  According to the seam welding apparatus 1 according to the above-described embodiment, the following effects can be obtained.

(1) The control device 30 heats the upper surface Wa of the workpiece W with the heat source 22 in the traveling direction A from the holding position by the pair of roller electrodes 21, and the heating position by the heat source 22 and the holding position by the pair of roller electrodes 21. Between, the temperature Tb of the lower surface Wb of the workpiece W is measured, GAP is estimated based on the measured temperature Tb of the lower surface Wb of the workpiece W, and the welding conditions are adjusted according to the GAP.
That is, the heat heated at the heating position is transferred from the upper surface Wa to the lower surface Wb of the workpiece W. At this time, the larger the gap between the base materials W1 and W2 in the workpiece W, the more difficult the heat is transferred to the lower surface Wb of the workpiece W. That is, the amount of heat transferred from the upper surface Wa to the lower surface Wb of the workpiece W and GAP have an inversely proportional correlation.
For this reason, if the correlation between the amount of heat transferred from the upper surface Wa of the workpiece W to the lower surface Wb and the size of the gap between the base materials W1 and W2 in the workpiece W is specified in advance, the temperature of the lower surface Wb of the workpiece W after heating is determined. GAP can be estimated by measuring Tb. Thereby, welding conditions can be adjusted according to GAP.
Therefore, even if the GAPs are different, the welding condition can be maintained constant by adapting to the welding conditions for growing the nuggets to the same size, and the quality of seam welding can be improved.

(2) The control device 30 adjusts the value of the welding current I supplied to the pair of roller electrodes 21 according to GAP.
That is, the larger the GAP, the higher the electrical resistance of the workpiece W, and the nugget grows only by supplying a small welding current I, and a high welding strength can be obtained. That is, in order to obtain a constant welding strength, the magnitude of GAP and the magnitude of welding current I have an inversely proportional correlation.
For this reason, if the correlation between the magnitude of the GAP and the magnitude of the welding current I is specified in advance, the value of the welding current I for obtaining a constant welding strength according to the magnitude of the GAP can be estimated.
Thereby, the value of the welding current I supplied to the pair of roller electrodes 21 can be adjusted according to the size of the GAP, and the welding conditions can be adapted to grow the nugget to the same size.

Second Embodiment
In the second embodiment, the detailed procedure when performing seam welding is different from that of the first embodiment, but the other parts are the same. Therefore, the characteristic part is demonstrated and description is abbreviate | omitted about the same structure.

  The storage unit 37 further stores the temperature-GAP characteristic shown in FIG. 8, the GAP-CAS characteristic shown in FIG. 9, and the CAS-welding current characteristic shown in FIG.

FIG. 8 is a diagram illustrating temperature-GAP characteristics, where the horizontal axis represents the temperature Tb of the lower surface Wb transferred from the upper surface Wa of the workpiece W, and the vertical axis represents the distance between the base materials W1 and W2 in the workpiece W. The size of the gap (hereinafter referred to as GAP).
Here, the temperature-GAP characteristic defines an inversely proportional correlation between the temperature Tb of the lower surface Wb transferred from the upper surface Wa of the workpiece W and the GAP. The temperature-GAP characteristic is based on the correlation that the heat transferred from the upper surface Wa of the workpiece W is less likely to be transferred to the lower surface Wb of the workpiece W as the GAP is larger. The temperature-GAP characteristic is set in advance by experiments or the like.

FIG. 9 is a diagram illustrating GAP-CAS characteristics, where the horizontal axis indicates GAP, and the vertical axis indicates the contact area between the base materials W1 and W2 in the workpiece W when the pair of roller electrodes 21 passes through. Indicates the size (hereinafter referred to as CAS).
Here, the GAP-CAS characteristic defines an inversely proportional correlation between GAP and CAS. The GAP-CAS characteristic is based on the correlation that the CAS becomes smaller as the GAP becomes larger. The GAP-CAS characteristic is set in advance by experiments or the like.

FIG. 10 is a diagram showing CAS-welding current characteristics, where the horizontal axis represents CAS and the vertical axis represents the magnitude of the welding current.
Here, the CAS-welding current characteristic defines a proportional correlation between CAS and the magnitude of the welding current I for obtaining a constant welding strength. The CAS-welding current characteristic is based on a correlation in which the larger the CAS is, the lower the electrical resistance of the workpiece W is, and the nugget does not grow unless a large welding current is supplied, and a high welding strength cannot be obtained. The CAS-welding current characteristic is set in advance through experiments or the like.

Next, a detailed procedure when performing seam welding will be described.
The control device 30 performs seam welding on the welding point (step S5). Specifically, the control device 30 performs seam welding by performing processing of steps S50 to S58 described later shown in FIG.
In addition, below, the process of step S5a-S5d different from the said embodiment is demonstrated.

  The control device 30 uses the temperature-GAP characteristic shown in FIG. 8 stored in advance in the storage unit 37 to calculate the GAP obtained according to the temperature Tb of the lower surface Wb of the workpiece W measured by the second temperature sensor 24. (Step S5a). Here, the calculated GAP is the size of the gap between the base materials W1 and W2 in the workpiece W at the measurement position measured by the second temperature sensor 24.

  Subsequently, the control device 30 uses the GAP-CAS characteristic shown in FIG. 9 stored in advance in the storage unit 37 to calculate the CAS calculated according to the calculated GAP (step S5b). Here, the calculated CAS is the size of the contact area between the base materials W1 and W2 in the workpiece W when the pair of roller electrodes 21 at the measurement position measured by the second temperature sensor 24 passes.

Then, the control apparatus 30 calculates the value of the welding current I calculated | required according to calculated CAS using the CAS-welding current characteristic shown in FIG. 10 previously memorize | stored in the memory | storage part (step S5c). Here, the calculated value of the welding current I is a welding current value necessary for obtaining a constant welding strength at the measurement position measured by the second temperature sensor 24.
Then, the control device 30 temporarily stores the calculated value of the welding current I at the measurement position measured by the second temperature sensor 24 in the storage unit 37.

  Subsequently, the welding power source control unit 33 supplies a welding current to the pair of roller electrodes 21 (step S5d). Here, the welding current supplied to the pair of roller electrodes 21 is a measurement position measured by the second temperature sensor 24 in the past once stored in the storage unit 37, and is a position where the pair of roller electrodes 21 are currently sandwiched. The value of the welding current I of Thereby, resistance welding is obtained in which a constant welding strength is obtained at the position where the pair of roller electrodes 21 are sandwiched.

  According to the seam welding apparatus 1 according to the above-described embodiment, in addition to the effects (1) and (2), the following effects can be obtained.

(3) The control device 30 estimates CAS according to GAP, and adjusts the value of the welding current I supplied to the pair of roller electrodes 21 according to the CAS.
That is, the larger the GAP, the smaller the CAS. That is, GAP and CAS have an inversely proportional correlation.
And the larger the CAS, the lower the electrical resistance of the workpiece W, and the nugget will not grow unless a large welding current is supplied, so that a high welding strength cannot be obtained. That is, in order to obtain a constant welding strength, CAS and the magnitude of the welding current have a proportional correlation.
For this reason, when the correlation between GAP and CAS and the correlation between CAS and the magnitude of welding current are specified in advance, the value of welding current I for obtaining a constant welding strength according to the magnitude of GAP is estimated. Can do.
Therefore, it is possible to maintain the welding state constant by setting the value of the welding current I for obtaining a constant welding strength according to the size of the GAP, and to improve the quality of seam welding by eliminating variations in the welding strength. it can.

  Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the scope of the present invention.

  In the above embodiment, the heat source 22 and the first temperature sensor 23 are fixedly arranged. However, for example, the heat source 22 and the first temperature sensor 23 may be mounted on the first support unit 50 and moved up and down similarly to the first roller electrode 21a.

  In the above embodiment, the value of the welding current I supplied to the pair of roller electrodes 21 is adjusted as a welding condition for growing the nugget to an equal size. However, the pressing force and the rotation amount of the pair of roller electrodes 21 may be adjusted.

  In 1st Embodiment, the value divided into three steps was used in temperature-GAP characteristic and GAP-welding current characteristic. However, scattered values divided into three stages may be used, or values that continuously change as in the second embodiment may be used. In the second embodiment, continuously changing values are used in the temperature-GAP characteristic, GAP-CAS characteristic, and CAS-welding current characteristic. However, scattered values may be used as in the first embodiment.

DESCRIPTION OF SYMBOLS 1 ... Seam welding apparatus 20 ... Welding apparatus main body 21 ... A pair of roller electrode 22 ... Heat source 24 ... 2nd temperature sensor 30 ... Control apparatus Tb ... Temperature of the lower surface of a workpiece | work I ... Welding current W ... Work W1, W2 ... Base material GAP ... Size of gap between base materials in workpiece CAS ... Size of contact area between base materials in workpiece Wa ... Upper surface Wb ... Lower surface A ... Advancing direction

Claims (6)

A welding apparatus body;
A pair of roller electrodes provided in the welding apparatus main body and sandwiching and rolling a workpiece in which at least two or more base materials are stacked; and
A heat source that is provided closer to the traveling direction than the pair of roller electrodes of the welding apparatus body, and heats one surface of the workpiece;
A temperature measuring means for measuring a temperature of the other surface of the workpiece between a heating position by the heat source and a sandwiching position by the pair of roller electrodes;
Control means for estimating the size of the gap between the base materials in the workpiece based on the temperature of the other surface of the workpiece measured by the temperature measuring means, and adjusting the welding conditions according to the size of the gap. And a seam welding apparatus.   The seam welding apparatus according to claim 1, wherein the control means adjusts a welding current value to be supplied to the pair of roller electrodes according to the size of the gap.   The control means estimates the size of the contact area between the base materials in the workpiece when the pair of roller electrodes passes according to the size of the gap, and according to the size of the contact area The seam welding apparatus according to claim 2, wherein a welding current value supplied to the pair of roller electrodes is adjusted. A seam welding method for sandwiching a work in which at least two base materials are laminated with a pair of roller electrodes, and performing resistance welding by applying pressure and energizing while rotating the pair of roller electrodes,
A heating step of heating one surface of the workpiece in a traveling direction from a sandwiching position by the pair of roller electrodes;
A measuring step of measuring a temperature of the other surface of the workpiece between a heating position in the heating step and a holding position by the pair of roller electrodes;
An adjustment step of estimating the size of the gap between the base materials in the workpiece based on the temperature of the other surface of the workpiece measured in the measurement step, and adjusting the welding conditions according to the size of the gap; And a seam welding method.   The seam welding apparatus according to claim 4, wherein the adjusting step adjusts a welding current value supplied to the pair of roller electrodes according to the size of the gap.   The adjusting step estimates the size of the contact area between the base materials in the workpiece when the pair of roller electrodes passes according to the size of the gap, and according to the size of the contact area. The seam welding method according to claim 5, wherein a welding current value supplied to the pair of roller electrodes is adjusted.

Images